“You shook up the World! My Mentor & My Friend. You changed my Life. Rest in Peace,” Smith, who EW has learned will be a pallbearer at Ali’s memorial service on Friday in Louisville, Kentucky, wrote alongside photos with The Champ.

Smith previously discussed portraying Ali during Sports Illustrated’s Sportsperson of the Year ceremony in 2015.

“For nearly two years, I worked to transform myself into the man who changed his name from Cassius Clay to Muhammad Ali and shook up the world,” he said. “And that’s really what makes my job so beautiful as an actor — for four, five months at a time I get to wear peoples’ lives. So I got to wear Muhammad Ali’s greatness. I got to study and feel and embody the soul of the man, from the foundations of Islam and the strength of his Muslim faith in his life, to the beautiful wake that he always leaves in his magnificent path.”